This was the cake I made for Dylan's second birthday. I made an allergen-free cake for his first birthday too, but it was a bit of a flop - this one was pretty much universally loved, and everyone was stunned that it was dairy and egg free! I have to give credit where credit is due - my friend Martina (Life on the Bay) gave me the link to the original recipe. I modified it a bit and it turned out really well! See the original at Vegan Chocolate Banana Cake and here's my slightly modified version:
2 cups flour
1 cup sugar
2/3 cup cocoa powder
1 1/2 tsp baking soda
1/4 cup dairy free margarine (I use Becel Vegan)
1 1/2 cup hot water
1 tsp vanilla extract
1 cup mashed/pureed bananas (you can use more, I used about 2 large bananas with a bit of water)
Preheat the oven to 350. Mix together dry ingredients in a large bowl. Add margarine, hot water, and vanilla extract and mix well. Add pureed bananas and blend thoroughly. Pour batter into a greased 9x13 cake pan and bake for 45-50m or until a toothpick inserted in the centre comes out clean. Let cake cool in the pan for 10-15m, then carefully transfer to a cooling rack to cool completely.
I frosted it with a simple white icing made with dairy free margarine, icing sugar, and vanilla extract (just add cocoa if you want a chocolate icing). The only challenge is that this icing really isn't good for decorating as it softens considerably at room temperature - if you want a decorated cake you would do better to use coconut oil as it's more solid at room temperature.
Enjoy!